In this paper, a theoretical framework for the design and evaluation of finite block-length analog fountain codes (AFC) towards ultra-reliable low latency communications (URLLC) is proposed. First, based on the achievable rate analysis and extrinsic information transfer (EXIT) analysis for AFC, we propose a weight adaptive (WA) AFC transmission scheme by introducing a limited feedback link, which can realize the lowest complexity AFC over a wide range SNRs. Further, by combining the conventional EXIT analysis and the dispersion perspective of mutual information, we propose a modified weight selection scheme for short block length WA-AFC (SWA-AFC) scheme. Simulation results show that our SWA-AFC scheme can achieve a superior performance than the existing AFC schemes, and approaching to the Polyansky-Poor-Verdu (PPV) bound.

中文翻译：

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用于超可靠低延迟通信的有限块长度模拟喷泉码

在本文中，提出了用于设计和评估有限块长度模拟喷泉码（AFC）以实现超可靠低延迟通信（URLLC）的理论框架。首先，基于 AFC 的可实现速率分析和外在信息传输 (EXIT) 分析，我们通过引入有限反馈链路，提出了一种权重自适应 (WA) AFC 传输方案，该方案可以在较宽的 SNR 范围内实现最低复杂度的 AFC。此外，通过结合传统的 EXIT 分析和互信息的分散视角，我们提出了一种用于短块长度 WA-AFC (SWA-AFC) 方案的改进权重选择方案。仿真结果表明，我们的 SWA-AFC 方案可以实现比现有 AFC 方案更优越的性能，并接近 Polyansky-Poor-Verdu (PPV) 界限。